3.The basic theory of plate tectonics is that along seafloor spreading zones, the continents are separating from one another. As they spread apart, magma comes to the surface and becomes new continental crust. As the tectonic plates move away from spreading zones, they collide with one another.
4.Well, during that time his theory was not widely accepted by the scientific community; also, lack of technological advancements allowed further research.
Hope this helps!
